Department of Medical and Biological Sciences, School of Medicine, University of Udine, P.le Kolbe 4, 33100 Udine, Italy.
Nitric Oxide. 2013 Apr 1;30:26-35. doi: 10.1016/j.niox.2013.01.002. Epub 2013 Jan 26.
Cell recurrence in cancer photodynamic therapy (PDT) is an important issue that is poorly understood. It is becoming clear that nitric oxide (NO) is a modulator of PDT. By acting on the NF-κB/Snail/RKIP survival/anti-apoptotic loop, NO can either stimulate or inhibit apoptosis. We found that pheophorbide a/PDT (Pba/PDT) induces the release of NO in B78-H1 murine amelanotic melanoma cells in a concentration-dependent manner. Low-dose PDT induces low NO levels by stimulating the anti-apoptotic nature of the above loop, whereas high-dose PDT stimulates high NO levels inhibiting the loop and activating apoptosis. When B78-H1 cells are treated with low-dose Pba/PDT and DETA/NO, an NO-donor, intracellular NO increases and cell growth is inhibited according to scratch-wound and clonogenic assays. Western blot analyses showed that the combined treatment reduces the expression of the anti-apoptotic NF-κB and Snail gene products and increases the expression of the pro-apoptotic RKIP gene product. The combined effect of Pba and DETA/NO was also tested in C57BL/6 mice bearing a syngeneic B78-H1 melanoma. We used pegylated Pba (mPEG-Pba) due to its better pharmacokinetics compared to free Pba. mPEG-Pba (30 mg/Kg) and DETA/NO (0.4 mg/Kg) were i.p. injected either as a single molecule or in combination. After photoactivation at 660 nM (fluence of 193 J/cm(2)), the combined treatment delays tumor growth more efficiently than each individual treatment (p<0.05). Taken together, our results showed that the efficacy of PDT is strengthened when the photosensitizer is used in combination with an NO donor.
癌症光动力疗法（PDT）中的细胞复发是一个尚未完全阐明的重要问题。目前越来越清楚的是，一氧化氮（NO）是 PDT 的调节剂。通过作用于 NF-κB/Snail/RKIP 生存/抗凋亡环，NO 可以刺激或抑制细胞凋亡。我们发现，原卟啉 IX/PDT（Pba/PDT）以浓度依赖性方式诱导 B78-H1 鼠无黑色素瘤细胞释放 NO。低剂量 PDT 通过刺激上述环的抗凋亡特性诱导低水平的 NO，而高剂量 PDT 则通过刺激高水平的 NO 抑制该环并激活细胞凋亡。当 B78-H1 细胞用低剂量 Pba/PDT 和 DETA/NO（一种 NO 供体）处理时，根据划痕和集落形成实验，细胞内 NO 增加，细胞生长受到抑制。Western blot 分析表明，联合治疗降低了抗凋亡 NF-κB 和 Snail 基因产物的表达，并增加了促凋亡 RKIP 基因产物的表达。还在携带同源 B78-H1 黑色素瘤的 C57BL/6 小鼠中测试了 Pba 和 DETA/NO 的联合作用。我们使用聚乙二醇化原卟啉 IX（mPEG-Pba），因为与游离原卟啉 IX 相比，其药代动力学更好。mPEG-Pba（30 mg/Kg）和 DETA/NO（0.4 mg/Kg）分别以单一分子或联合形式通过腹腔注射给药。在 660nm 光激活（193 J/cm2 通量）后，与单独治疗相比，联合治疗更有效地延迟肿瘤生长（p<0.05）。总之，我们的结果表明，当将光敏剂与 NO 供体联合使用时，PDT 的疗效得到增强。
